Nikon mirrorless has a 1/2.3 sensor

Nikon Rumors seems fairly convinced this is a genuine image of an upcoming mirrorless mount:

The shock news is the small size of the sensor (1/2.3 or 1/2.5?)

My inexpert personal view of the camera biz is buyers of small-sensor cameras will be more likely to buy fixed-lens compacts, but Nikon has an SLR business to protect and doesn't want to risk that competing with their own mirrorless.